1. Field of the Invention
The present invention relates to a key protection structure for an electronic apparatus including an electronic control device such as a timer or a temperature controller.
2. Conventional Art
In a conventional electronic apparatus, as shown in FIG. 15, an operation section 200 is disposed in the front face. The operation section 200 is configured by a switch unit (not shown) and a front cover 209. The switch unit comprises first, second, and third switches 210, 211, and 212, and a printed circuit board (not shown) on which electronic parts are mounted and a conductor pattern (not shown) is formed.
In a face 209a of the front cover 209, a first switch operation hole 213 and an arcuate display window 213A, a second switch operation hole 214, and a third switch operation hole 215 are formed. The second and third switch operation holes 214 and 215 have rectangular display windows 214A and 215A, respectively.
In the first switch operation hole 213, a setting knob member 216 disposed on an operation shaft (not shown) of the first switch 210 is placed so as to forward protrude from the face 209a of the front cover 209. In the second switch operation hole 214, a setting knob member 217 disposed on an operation shaft (not shown) of the second switch 211 is placed so as to forward protrude from the face 209a of the front cover 209. In the third switch operation hole 215, a setting knob member 218 disposed on an operation shaft (not shown) of the third switch 212 is placed so as to forward protrude from the face 209a of the front cover 209.
When setting is to be performed through the first, second, or third switch 210, 211, or 212, therefore, the worker rotates or operates the setting knob member 216, 217, or 218.
In the operation section 200 used in another conventional electronic apparatus, as shown in FIG. 16, the setting knob members 216, 217, and 218 are not disposed in the first, second, and third switches 210, 211, and 212, and cross grooves 219, 220, and 221 may be disposed in the centers of knobs (not shown) of the first, second, and third switches 210, 211, and 212, respectively. The cross groove 219 of the first switch 210 is operably positioned in the first switch operation hole 213 of the front cover 209. The cross groove 220 of the second switch 211 is operably positioned in the second switch operation hole 214. The cross groove 221 of the third switch 212 is operably positioned in the third switch operation hole 215.
When setting is to be performed through the first, second, or third switch 210, 211, or 212, therefore, a tool (not shown) having an operation portion (not shown) in which an engaging projection (not shown) of a cross shape is formed at the tip end is used. Specifically, the operation portion of the tool is inserted into the first switch operation hole 213 (the second switch operation hole 214 or the third switch operation hole 215) of the front cover 209. The cross engaging projection of the operation portion is engaged with the cross groove 219 (220 or 221) of the first switch 210 (the second switch 211 or the third switch 212). Thereafter, the tool is rotated, so that the first switch 210 (the second switch 211 or the third switch 212) is rotated to change the setting.
In the former one of the conventional electronic apparatuses described above, for example, the setting knob member 216 of the first switch 210 is placed in the first switch operation hole 213 so as to forward protrude from the face 209a of the front cover 209. Also the setting knob member 217 of the second switch 211 relating to the second switch operation hole 214, and the setting knob member 218 of the third switch 212 relating to the third switch operation hole 215 are placed in a similar manner as the setting knob member 216. Therefore, any one can rotate the setting knob member 216, 217, or 218 to change preset value, irrespective of whether the contents of the work are those allowed to only a specific worker or not. Consequently, such an apparatus has a problem in that it is impossible to prevent a preset value from being intentionally changed.
In the latter one of the conventional electronic apparatuses, the cross groove 219 of the first switch 210 is positioned in the first switch operation hole 213 of the front cover 209, the cross groove 220 of the second switch 211 is positioned in the second switch operation hole 214, and the cross groove 221 of the third switch 212 is positioned in the third switch operation hole 215. Therefore, the cross grooves 219, 220, and 221 can be easily visually recognized from the outside. When a tool having an operation portion the tip end of which has a cross shape is used, therefore, any one (the user or the like) can rotate the setting knob member 216, 217, or 218 to change preset value, irrespective of whether the contents of the work are those allowed to only a specific worker or not. Consequently, also such an apparatus has a problem in that it is impossible to prevent a preset value from being intentionally changed.
The invention has been conducted in view of the above-discussed problems. It is an object of the invention to provide a key protection structure for an electronic apparatus which can prevent a preset value of a switch from being intentionally changed by the user or the like, and which, even when no software exists, can ensure a key protection function by a simple structure.
In order to attain the object, according to a key protection structure for an electronic apparatus of a first aspect of the invention, in an electronic apparatus in which a switch operation hole corresponding to a switch operation portion of each of switches that are incorporated in a main unit of the apparatus is disposed in the apparatus main unit, and the switch is activated by operating the switch operation portion through the switch operation hole, the switch operation portion is covered by covering means in which covering is cancelled only by a special tool.
According to this configuration, when setting of the switch is once ended, the switch operation portion is covered by the covering means in which the covering is cancelled only by a special tool, whereby the switch can be locked (key-protected) so as not to be externally operated.
Therefore, the preset value can be prevented from being intentionally changed by a person who do not have the special tool, such as the user. Even an electronic apparatus in which software for key protection is not prepared can be provided with a key protection function by a simple structure.
Conventionally, some apparatuses have an input terminal or a switch for activating key protection, and realize a key protection function on the basis of an input operation performed on the terminal or the switch. In this case, such an apparatus requires a dedicated input terminal or switch. According to the invention, such an input terminal or a switch can be eliminated. In some electronic apparatuses; key protection is performed by covering the whole of a front portion by a cover. In this case, there arises a disadvantage that the cover may no t be removed away. According to the invention, it is possible to obtain a structure which can eliminate such a disadvantage and realize also space saving. Furthermore, the key protection level can be changed depending on the kind of the special tool, i.e., a dedicated key.
In order to attain the object, a key protection structure for an electronic apparatus of a second aspect of the invention is configured so that, in the key protection structure for an is electronic apparatus of the first aspect of the invention, the covering of the switch operation portion by the covering means is performed on one or more of the switches which is required to be covered.
According to this configuration, the same effects as the above-described effects of the first aspect of the invention can be attained. Since the covering of the switch operation portion by the covering means is performed only on one or more of the switches which is required to be covered, moreover, the switches can be classified so as to prevent a field worker from erroneously operate the switches. As a result, an operation section which is easy for the worker to operate can be obtained.
In order to attain the object, according to a key protection structure for an electronic apparatus of a third aspect of the invention, in an electronic apparatus in which a switch operation hole corresponding to a switch operation portion of each of switches that are incorporated in a main unit of the apparatus is disposed in the apparatus main unit, and the switch is activated by operating the switch operation portion through the switch operation hole, the structure comprises: a shutter which covers the switch operation hole and cancels the covering; a shutter operation portion which is disposed in the shutter and with which a tool shutter operation portion of a special tool is to be disengeably engaged; and a shutter operation hole which is disposed in the apparatus main unit, which corresponds to the shutter operation portion of the shutter, and into which the special tool is to be inserted.
According to this configuration, when setting of the switch is once ended, the tool shutter operation portion of the special tool is inserted into the shutter operation hole, and the tool shutter operation portion is then engaged with the shutter operation portion of the shutter. Thereafter, the shutter is activated by operating the special tool. The shutter is then moved immediately above the switch to close the switch operation hole, whereby the switch can be locked (key-protected) so as not to be externally operated.
Therefore, the preset value can be prevented from being intentionally changed by a person who do not have the special tool, such as the user. When one or more of the switches is locked by means of the shutter, the switches can be classified so as to prevent a field worker from erroneously operate the switches. As a result, an operation section which is easy for the worker to operate can be obtained. Furthermore, even an electronic apparatus in which software for key protection is not prepared can be provided with a key protection function by a simple structure.
Conventionally, an input terminal or a switch for activating key protection is required. However, such an input terminal or a switch can be eliminated. When key protection is performed by covering the whole of a front portion of an electronic apparatus by a cover, there arises a disadvantage that the cover may not be removed away. According to the invention, it is possible to obtain a structure which can eliminate such a disadvantage and realize also space saving. Furthermore, the key protection level can be changed depending on the kind of the special tool, i.e., a dedicated key.
In order to attain the object, a key protection structure for an electronic apparatus of a fourth aspect of the invention is configured so that, in the key protection structure for an electronic apparatus of the third aspect of the invention, the structure comprises positioning means for positioning the shutter at either of a covering position where the shutter covers the switch operation hole, and a covering canceling position where the shutter does not cover the switch operation hole.
According to this configuration, the same effects as the above-described effects of the third aspect of the invention can be attained. Furthermore, the shutter can be positioned at either of a covering position where the shutter covers the switch operation hole, and a covering canceling position where the shutter separates from the switch operation hole, by the positioning means.
In order to attain the object, a key protection structure for an electronic apparatus of a fifth aspect of the invention is configured so that, in the key protection structure for an electronic apparatus of the third aspect of the invention, the structure comprises moving distance limiting means for limiting a moving distance of the shutter.
According to this configuration, the same effects as the above-described effects of the third aspect of the invention can be attained. Furthermore, the moving distance of the shutter can be regulated by the moving distance regulating means.
In order to attain the object, a key protection structure for an electronic apparatus of a sixth aspect of the invention is configured so that, in the key protection structure for an electronic apparatus of the third aspect of the invention, the shutter operation portion is an engaging portion which has a special shape, and with which the tool shutter operation portion of the special tool is to be disengeably engaged.
According to this configuration, the same effects as the above-described effects of the third aspect of the invention can be attained. Furthermore, the shutter operation portion is an engaging portion which has a special shape, and with which the tool shutter operation portion of the special tool is to be disengeably engaged. Even when an ordinary tool such as a hexagonal wrench is used, therefore, the shutter cannot be activated (rotated). As a result, the switch can be locked (key-protected) so as not to be externally operated.
In order to attain the object, according to a key protection structure for an electronic apparatus of a seventh aspect of the invention, in an electronic apparatus in which an operation section consisting of a switch unit and a front cover is disposed in a main unit of the apparatus, plural switches are disposed by using the switch unit as a base, a switch operation hole corresponding to a switch operation portion of each of the switches is disposed in the front cover, and the switch is activated by operating the switch operation portion through the switch operation hole, the shutter is configured by forming a covering portion at a tip end of a shaft, the covering portion being perpendicular to the shaft, and forming an engaging portion with which a tool shutter operation portion of a special tool is to be disengeably engaged, in a tip end face of the shaft, plural shutter holding cylinders are disposed in a face of the base, a shutter operation hole which corresponds to the engaging portion of each shutter, and into which the special tool is to be inserted is disposed in the front cover, the shutter is disposed on the base while the shaft is inserted into and passed through corresponding one of the shutter holding cylinders, and the engaging portion of the shutter is positioned in the shutter operation hole by superposing the front cover on the switch unit.
According to this configuration, when setting of the switch is once ended, the tool shutter operation portion of the special tool is inserted into the shutter operation hole, and the tool shutter operation portion is then engaged with the engaging portion of the shutter. Thereafter, the shutter is activated by operating the special tool. The covering portion is then moved immediately above the switch to close the switch operation hole, whereby the switch can be locked (key-protected) so as not to be externally operated.
Therefore, the preset value can be prevented from being intentionally changed by a person who do not have the special tool, such as the user. When one or more of the switches is locked by means of the shutter, the switches can be classified so as to prevent a field worker from erroneously operate the switches. As a result, the operation section which is easy for the worker to operate can be obtained. Furthermore, even an electronic apparatus in which software for key protection is not prepared can be provided with a key protection function by a simple structure.
Conventionally, an input terminal or a switch for activating key protection is required. According to the invention, such an input terminal or a switch can be eliminated. In some electronic apparatuses, key protection is performed by covering the whole of a front portion of an electronic apparatus by a cover. In this case, there arises a disadvantage that the cover may not be removed away. According to the invention, it is possible to obtain a structure which can eliminate such a disadvantage and realize also space saving. Furthermore, the key protection level can be changed depending on the kind of the special tool, i.e., a dedicated key.